Pocket Beach Vulnerability to Sea-level Rise

The objective of this paper is to quantify the role of relative sea-level rise in the retreat of the shoreline and to evaluate this retreat in terms of future sea-level rise on 23 pocket beaches in Provence (France). Between 1896 and 1998, all of the investigated pocket beaches underwent erosion, with an average retreat of 12.1 (+/- 3.5) m. Making use of the flooding principle, and assuming a relative sea-level rise of +11 cm between 1896 and 1998, we obtain an average shoreline retreat of 5.8 (+/- 3.5) m. A comparison between measured average retreat and calculated average retreat suggests that sea-level rise is one of the main factors influencing shoreline retreat (50% of shoreline retreat can be explained by sea-level rise). The position of the shoreline for 2100 is evaluated not only by using the historical shoreline trend and the flooding method but also by adding the historical shoreline trend and the flooding concept in the case of an increase in sea-level of about +44 cm (for 2100). On the investigated pocket beaches, the presence of a cliff 'blocking' the landward migration of the profile will lead to a significant reduction in beach width. Thus, we envisage that the pocket beaches will lose 75 % to 97 % of their present surface area. In other words, we predict the eventual disappearance of the pocket beaches in Provence.